[Config] Configuration management: Centralized config, validation, and environment-specific configs

[OneByJorah]

Configuration Management Checklist

• Centralized configuration:
  • Move all config to structured format (YAML/TOML/JSON) with environment overlays
  • Add config validation schema (JSON Schema / CUE / KCL)
  • Support environment-specific configs (dev/staging/prod)
  • Add config templating for docker-compose (Helm/Compose/Envsubst)
• Environment variable management:
  • Document all required/optional env vars in one place
  • Add env var validation at startup
  • Add .env.example with all variables documented
  • Support loading from multiple sources (file, env, secrets manager)
• Config versioning:
  • Version config schema
  • Migration path for config changes
  • Document config changes in CHANGELOG
• Configuration as code:
  • Store config in Git (except secrets)
  • Use separate repos for environment configs if needed
  • Add config drift detection
• Service configuration:
  • SearXNG: externalize settings.yml to config management
  • Camofox: document all config options
  • Honcho: externalize config
  • Obsidian: document config
  • Qdrant: externalize config
  • PostgreSQL/Redis: externalize config
• Add config documentation to docs/CONFIGURATION.md